I did check with Subaru before buying my type UK as I wanted to understand the differences also from wikipedia http://en.wikipedia.org/wiki/Subaru_Impreza
They are versions of Impreza WRX STI for the UK market, with specific tuning by Prodrive. WRX STI 330S includes increased engine power to 330 PS (243 kW; 325 hp). WRX STI 380S includes increased engine power to 380 PS (279 kW; 375 hp), new wheels, an upgraded body kit. The vehicles were unveiled in British Auto Show.
Subaru announced, on September 10, 2008, that the 380S variation would not be produced, due to homologation and specification difficulties. However, the regular 330S model did enter production as the "WRX STI Type UK".